Various manufacturing and other processes involve measuring and collecting optical radiation data, in particular spectral emission characteristics, of a source of optical radiation. The manufacturing or other process may be a process for which optical radiation is used as part of performing the process or in which optical radiation is generated by the process. In some instances, such as imaging applications, it may be desirable to measure and determine the spectral emission characteristics of the ambient light.
While various techniques are available, some known techniques provide only global or averaged measurements for a region of the process. For example, an array of photodiodes can be provided to measure incident light of various wavelengths. The response of the photodiodes, however, generally depends on the intensity of the incident radiation as well as on the wavelength of the radiation. As a result, it may not be possible to assign a particular photocurrent value to a unique wavelength. For example, if ambient light is being detected, it may not be possible to correlate a particular value of photocurrent with a specific wavelength of specific part of the spectrum.
Further, some light sources have multiple emission peaks. For example, sodium vapor lamps generate two emission peaks near 589 nm Those peaks, however, are outside typical red (R), blue (B) and green (G) filters. Thus, a sensor configured only with these filters will be unable to detect the sodium-vapor lines.